1. Field
This disclosure relates generally to non-volatile memories (NVMs), and more specifically, to brownout recovery techniques for NVMs.
2. Related Art
An NVM commonly has program and erase cycles that to be effective need to be uninterrupted. On occasion, however, an interruption does occur. This is typically most likely to occur during an erase operation because erase operations are typically quite long because erase operations commonly include many steps such as pre-erase program, erase, and soft programming. This interruption is normally a result of a loss or reduction in power and thus called a brownout. The brownouts can occur at any point in the erase operation and information as to precisely what state that is may be impossible or at least difficult to store. Also, the cells have a distribution so the precise state of the cells is similarly difficult to know even if the precise point in the erase operation where the brownout has occurred is precisely known. Thus, brownout recovery generally is simply to repeat the erase operation from the beginning. Nonetheless, there are brownouts that result in a subsequent failure to erase, especially when some cells are left in the over-erased state as a result of the brownout.
Accordingly, it is desirable to provide a technique that provides a reduction in failures due to brownout.